The present invention concerns a process for preparing reinforced glass matrix composites.
Generally, fabrication of glass matrix composites is accomplished by impregnating a mat of fibrous material with a glass slurry. The impregnated fibers are then dried and stored as a prepreg or used directly. In any case, they are cut into desired form and molded under pressure and heated to fuse the glass matrix. Typical preparations as described above are disclosed in U.S. Pat. Nos. 4,511,663 and 4,485,179.
U. K. Patent Application 52023/68 discloses a technique where a continuous length of glass fibers is first pulled over and under spreading rollers to form a tape and then into a bath containing a glass powder slurry. Excess slurry is removed from the wet tape before it is wound onto a flat-sided drum so that the turns bond together. The turnings are removed and hot pressed. Modifications of this process can be found in U.S. Pat. No. 3,681,187.
U.S. Pat. No. 4,263,367 attempts to improve the reinforcement of glass matrix composites by employing premanufactured isotropically laid, i.e., in-plane randomly oriented fiberst graphite paper mats. After removing the binder material from the mats by solvent immersion or burning, the mats are dipped into a glass slurry. The mats are then stacked with alternating layers of powdered glass and hot pressed. The randomly oriented reinforcing fibers provide enhanced mechanical strength to the glass matrix composites.
Still another attempt to prepare glass matrices with reinforcing fibers is described in the article by Sambell, Bowen and Phillips, "Carbon Fiber Composites with Ceramic and Glass Matrices", Journal of Material Science, 7 (1972) at 663. Their process involves dispersing chopped carbon fibers and powdered matrix material in isopropyl alcohol. The mixture is continuously agitated while the alcohol is removed by infrared radiant heat until the mixture has a stiff consistency. The mixture is then loaded into a die assembly and hot pressed.
While the above methods are satisfactory, they are quite labor intensive. Simple, more efficient methods with good composition control are desired.